Learning-induced plasticity in the barrel cortex is disrupted by inhibition of layer 4 somatostatin-containing interneurons

ABSTRACT Learning-related plasticity in the cerebral cortex is linked to the action of disinhibitory circuits of interneurons. Pavlovian conditioning, in which stimulation of the vibrissae is used as conditioned stimulus, induces plastic enlargement of the cortical functional representation of vibrissae activated during conditioning, visualized with [ 14 C]-2-deoxyglucose (2DG). Using layer-specific, cell-selective DREADD transductions, we examined the involvement of somatostatin- (SOM-INs) and vasoactive intestinal peptide (VIP-INs)-containing interneurons in the development of learning-related plastic changes. We injected DREADD-expressing vectors into layer IV (L4) barrels or layer II/III (L2/3) areas corresponding to activated vibrissae. The activity of interneurons was modulated during training, and 2DG maps were obtained 24 h later. In mice with L4 but not L2/3 SOM-INs suppressed during conditioning, the plastic change of whisker representation and the conditioned reaction were absent. No effect of inhibiting VIP-INs was found. We report that the activity of L4 SOM-INs is indispensable for learning-induced plastic change.